Checkpoint files of different replicas correspond to different timesteps

GROMACS version: 2020.4-MODIFIED
GROMACS modification: Yes - Patched with Plumed


I have been seeing the following error upon restarting my multi simulation with mdrun:

Fatal error: The initial step is not consistent across multi simulations which share the

Indeed the checkpoints for each replica do not correspond to the same initial step. I would like to understand why this is so and how to enforce synchronized checkpoint files. In my simulation no exchanges are attempted but there is a synchronization between replicas every 500 steps enforced by Plumed.

Looking forward to your feedback.

Best regards,

Pablo Piaggi